1. Field of the Invention
The present invention relates generally to a vehicular steering system. More particularly, the invention relates to a vehicular steering system wherein front and rear wheels are steered by operation of a steering wheel.
2. Description of Relevant Art
The present applicants have previously provided a vehicular steering system wherein both front and rear wheels are steered by operation of a steering wheel whereby problems associated with vehicles of the type wherein only front wheels are steered, such as the difference in generation time of a lateral force between front and rear wheels and the disagreement between the vehicular direction and the tangential direction of turning locus, can be overcome. In such a vehicle, it is desirable to steer the rear wheel in the manner described hereinbelow together with steering of the front wheel in consideration of the fact that the steering angle of the steering wheel operated by the vehicle driver substantially differs in accordance with travelling speeds of the vehicle.
When the aforesaid vehicle is travelling at a relatively high speed, the steering wheel is rotated a relatively small angular extent and in this case the rear wheel is steered in the same direction as that of the front wheel so as to improve the steering performance of the vehicle. On the other hand, when the vehicle is travelling at a relatively low speed, the steering wheel is rotated a relatively large angular extent and in this case the rear wheel is steered in a direction opposite to that of the front wheel, so as to improve the turning operability of the steering wheel. In this latter case, in some particular uses of the vehicle it is desirable to maintain the steering angle of the rear wheel at substantially zero so that the turning operability of the steering wheel is substantially the same as that of conventional vehicles wherein only the front wheel is steered.
The present invention effectively overcomes the aforementioned problems in the field of vehicular steering systems by providing a novel vehicular steering system construction.